The overall process for copper smelting is well-known, for example, as described in JP Patent Publication Heisei 11-256250, JP Patent Publication Heisei 11-335750, and JP Patent Publication Heisei 11-335751. Smelting of copper is performed for example by charging concentrate melted in a smelting furnace such as flash furnace to a converter, removing Fe and S from the concentrate to produce crude copper of copper grade 98-99% by blowing in air or oxygen enriched air to the converter from a plurality of tuyeres arranged at the lower part of the sidewall of the converter and finally refining the copper by electrolytic refining in an electrolysis solution to obtain electrolytic copper of copper grade over 99.99%. The converter employed in this process is provided with a so-called PS converter (Pierce Smith converter) which is a furnace body in a shape of a transversely-situated cylinder configured to incline back and forth by an electric motor to facilitate charging and draining of the concentrate and as already explained above, it is also provided with a couple dozen of tuyeres for blowing in air or oxygen-enriched air.
The PS converter is operated in batches and matte necessary for each batch is carried down by ladle from the smelting furnace in the preceding process. One batch amount of matte charged to the converter is then blown within the converter. In this blowing process, there are 2 refining stages, slag-making operation and copper-making operation. The slag-making operation is a process of removing Fe and S in the matte by oxidation, in which oxidized S is discharged with exhaust gas as SO2 gas while FeO having higher melting point is removed by charging silicate ore consisting primarily of SiO2 into the furnace so that it binds with FeO to produce slag with lower melting point, and then discharged from the furnace after the completion of the first slag-making operation.
The solution within the furnace decreases when the slag is discharged from the furnace after the completion of the first slag-making operation, so an additional amount of matte is charged to the furnace to carry out the second slag-making operation. Conventionally, the slag-making operation is repeated twice in general particularly when the matte produced in the smelting furnace is around copper grade 60%. The solution after discharging the slag from the furnace after the first slag-making operation is called “white metal” having a copper grade of about 75% consisting mainly of Cu2S apart from a slight remaining amount of Fe. After the slag-making operation is the copper-making operation in which S in Cu2S is removed by oxidation to finally produce crude copper having a copper grade of about 98-99%.
Since 7˜12% of SO2 is included in the exhaust gas generated during the operation of the PS converter, an exhaust gas hood is provided to prevent the gas from leaking outside while the gas is collected by an aspirator to produce sulfuric acid. However, the inner surface of the jacket of the exhaust gas hood disposed near a charging and discharging hole of the PS converter is more likely to be attached with matte-sticking, so-called “beko” in Japanese, which is formed by aggregation and solidification of components such as Cu2S, FeS and FeO included in the exhaust gas. This may hinder the operation since the matte-sticking may gradually grow bigger with the operation and cause it to block the gas flue and suddenly fall off. The matte-sticking is more likely to be formed on the surface of the rear jacket of the exhaust gas hood near the charging and discharging hole of the PS converter, and much time was required to remove the matte-sticking. Accordingly, an apparatus for mechanically removing such matte-sticking has been proposed in JP Patent Publication Heisei 8-159663.
Matte-sticking growing bigger with the slag-making operation not only interferes with the operation by blocking the gas flue but also hinders the operation by suddenly falling off from the surface due to the inclined configuration of the rear jacket, and bumping into other facilities to cause further damages. Hence it is necessary to reliably scrape and remove the matte-sticking before it grows big as to fall off spontaneously. Conventionally, removal of matte-sticking formed on the gas flue was done by hand, but since this required long hours of operation suspension, an improvement is called for.
Apparatuses to remove matte-sticking mechanically have been proposed such as in the references above, but in the case of operation in converters, the matte-sticking accumulated to the inclined and broad surface of the rear jacket should be removed over almost its entire surface. Hence, an apparatus which can regularly as well as simply and safely remove the matte-sticking has been needed.